Engineering Chemistry MCQ (Polymeric Composites)

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Engineering Chemistry MCQ (Polymeric Composites)

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Polymeric Composites

1. Which of the following does not combine with fiber to give composites?
a) Metals
b) Ceramics
c) Non-metals
d) Polymers
Answer: c
Explanation: Composites are obtained from metals, ceramics and polymers by
adding fibers to them. Non-metals do not contribute to the formation of composites.

2. Which of the following is not a property of matrix materials which are modified by adding particulate fillers?
a) Improved performance at elevated temperature
b) Decrease in surface hardness
c) Modification in electrical conductivity
d) Improved abrasion resistance
Answer: b
Explanation: Improved performance at elevated temperature, decrease in surface
hardness, modification in electrical conductivity, improved abrasion resistance are
some of the properties of matrix materials which are modified by adding particulate fillers.

3. What is the aspect ratio?
a) Length to diameter ratio
b) Length to depth ratio
c) Depth to length ratio
d) Diameter to length ratio
Answer: a
Explanation: Aspect ratio is defined as length to diameter ratio. The aspect ratio is
expressed as two numbers separated by a colon (x:y). The values x and y do not
represent actual length and diameter but, rather, the relationship between length and diameter.

4. Which of the following type of composite is not classified under the category of number of layers?
a) Unidirectional fibre reinforced
b) Laminar
c) Sandwich panels
d) Glass-fibre reinforced
Answer: d
Explanation: Glass-fiber reinforced composite is not classified under the category of
number of layers. All the other options are classified under this category.

5. The matrix phase controls the environmental resistance of the composites.
a) True
b) False
Answer: a
Explanation: The matrix phase controls the environmental resistance of the
composites. Since Polymer Matrix Composites combine a resin system and
reinforcing fibers, the properties of the resulting composite material will combine
something of the properties of the resin on its own with that of the fibers on their own.

6. Select the incorrect statement from the following option.
a) Laminar composites consist of 2-D sheets that are stacked and subsequently cemented together
b) Sandwich panels consist of two stronger outer sheets separated by a layer of less dense core material
c) Core material should be heavy-weight and low corrosion resistance
d) The stiffness of the sandwich panel increases as the core thickness increases
Answer: c
Explanation: Core material should be light-weight and high corrosion resistance. All
the other options are correct. Laminar composites consist of 2-D sheets that are
stacked and subsequently cemented together. Sandwich panels consist of two
stronger outer sheets separated by a layer of less dense core material and the
stiffness of the sandwich panel increases as the core thickness increases.

7. One of the most popular types of core material used is ____________
a) Metal foam
b) Honeycomb
c) Glass
d) Plastic
Answer: b
Explanation: One of the most popular types of core material used is a honeycomb
structure. Rest all options are not used widely as core material should be lightweight and high corrosion resistance.

8. The flexural stiffness of the sandwich panel is proportional to the _____________ of core thickness.
a) Square
b) Square root
c) Inverse
d) Cube
Answer: d
Explanation: The flexural stiffness of the sandwich panel is proportional to the cube
of core thickness. It increases with the thickness of the core material.

9. Which of the following is not an application of a sandwich panel?
a) Fabrication of wings of aircrafts
b) Design of ships, boat hulls
c) Conveyor belts
d) Fabrication of roofs, floors and walls of buildings
Answer: c
Explanation: Fabrication of wings of aircrafts, design of ships, boat hulls and
fabrication of roofs, floors and walls of buildings are some of the applications of
sandwich panel. Conveyor belts are not the application of sandwich panel.

10. When fibers are used as a dispersed phase for the reinforcement of matrices, the resultant composites are known as ____________
a) Glass-fiber reinforced
b) Carbon-fiber reinforced
c) Wood-fiber reinforced
d) Unidirectional-fiber reinforced
Answer: a
Explanation: When fibers are used as a dispersed phase for the reinforcement of
matrices, the resultant composites are known as glass-fiber reinforced. Glass-fiber
reinforced composites should have low density, high impact resistance, high tensile
strength and excellent chemical and corrosion resistance.

11. Which of the following is not a characteristic of glass-fiber reinforced composites?
a) Low density
b) Low impact resistance
c) High tensile strength
d) Excellent chemical and corrosion resistance
Answer: b
Explanation: Glass-fiber reinforced composites should have low density, high impact
resistance, high tensile strength and excellent chemical and corrosion resistance.

12. Which of the following is an application of glass-fiber reinforced composites?
a) Adhesives
b) Conveyor belts
c) Design of ships
d) Automotive parts
Answer: d
Explanation: Automotive parts, storage tanks, plastic pipes etc are some of the
applications of glass-fiber reinforced composites.

13. Which of the following is used as reinforcement in advanced polymer matrix composite?
a) Glass-fiber reinforced
b) Carbon-fiber reinforced
c) Wood-fiber reinforced
d) Unidirectional-fiber reinforced
Answer: b
Explanation: Carbon-fiber reinforced is used as reinforcement in advanced polymer matrix composite, which requires retention of desired properties.

14. Which of the following is not an advantage of composites?
a) Easy to manufacture and durable
b) Excellent thermal, mechanical and chemical properties
c) Heavy-weight and non-versatile
d) Economical and tailor made
Answer: c
Explanation: Composites are light-weight and versatile. All the other options are
correct. They are easy to manufacture and durable, have excellent thermal,
mechanical and chemical properties and economical and tailor made.

15. The principal applications of composites are in transportation industry, consumer products and industrial and scientific equipment.
a) True
b) False
Answer: a
Explanation: The principal applications of composites are in transportation industry,
consumer products and industrial and scientific equipment. But composites can fail
on the microscopic or macroscopic scale. Compression failures can occur at both
the macro scale or at each individual reinforcing fiber in compression buckling.
Tension failures can be net section failures of the part or degradation of the
composite at a microscopic scale where one or more of the layers in the composite
fail in tension of the matrix or failure of the bond between the matrix and fibers.